This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Morphological long-term development of human carotid artery bifurcation has been studied recently. The most important findings when comparing morphologic images of the carotid bifurcation obtained from infancy to adulthood were the substantial growth of the internal carotid artery (ICA) with age and the development of a carotid sinus at the root of the ICA. It appears that the carotid bulb in humans develops as a result of arterial remodeling that coincides with maturation and growth of the brain and occurs at approximately the same time that hormonal changes take place during puberty. Although the reasons for its appearance are unknown, it has been hypothesized that the function of the sinus is to slow the blood flow and reduce the pulsatility in order to protect the brain. It is interesting to speculate why this unique bifurcation develops in this way. Therefore, we propose phase-contrast magnetic resonance (MR) flow experiments of human carotid artery bifurcation in four post-natal stages, Group I (0-2 years), Group II (3-9 years), Group III (10-19 years), and Group IV (20-36 years), respectively. Morphologically averaged human carotid bifurcations in each group are created in 3-D design software. The compliant silicone replicas of the 3-D computer designed vascular models are then fabricated using rapid prototyping techniques. After the vascular replicas are obtained, phase-contrast MR flow experiments are performed to investigate the local hemodynamic effect of morphological long-term changes in human carotid bifurcation. This study may give us understanding of hemodynamic mechanisms for the initiation and progression of carotid bifurcation atherosclerotic occlusive disease.